Beneficiation of ores



`March 9 1926.

C. F. MGCORMACK BENVEFICIATION OF QRES Filed May 5.-

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To all whom it may concern:

p flaw? lilly CUP Patented Mar. 9,1925. UNITED STATES 1,575,852 PATENTOFFICE-a.

CLYDE IP. MCCORMACK, 0F CLEVELAND, OHIO.

,i I .application 'led Hay 5,

Be it known that I, CLYDE P.' MCCOR- MACK, a'citizen ofthe UnitedStates, and a resident ot.Cleveland, county of Cuyahoga, and Stateof'Ohio, have invented a new and useful Improvement in the Beneciationof Ores, of which `the following is specification, the principle of theinvention being herein explainedand the best inode vin which I havecontemplated applying that principle, so as to distinguish it from otherinventions. v The present improvements rclatefv more particularly to .-a)method of treating an oxidized iron ore or inetal-bearilig productcontaining aluminum, Ichromium and nickel. Typical of Vsuch iron oresare the soft iron ores of the north coast of the island o Cuba,v whichconsist essentially of oxides oi iron and alumina and contain"relatively small amounts of the metals chromium and nickel, such-ironore in its raw state beinginon-merchantable due to veryhiglgi mo ptr reand `volatile content in `addition 'to suh alumina, chromium andlnickel.

The object of, he present 'nvention is 'toy beneticiate such-- an ore byremoving the"4 aluminum, chromium and v*nickel in such form that thesevaluable constituents ymay. be segregated yand utilized in any way thatmay be desired, and at the same time, Aand principally, the iron oxideis substantially. freed from such other metals 'and is i'n forltl titfor blast furnace sm'elting. To'the a'ccomplishment of the foregoing andrelated ends, said invention, then, consists of the steps hereinafter fully described and pnrtic-` ularlv pointed out in the claims, theanne`xedrawing and-the following description setting forth in detail certainmeans and one mode of carrying out the invention, such disclosedmeansand mode illustratin however, but one of various ways in whio theprinciple of the invention may be used.

In said annexed drawing The single figure there appearing is adiagrammatic representation, on the order of a flow sheet, illustratingboth the sequence ot steps and the arrangement of.`a

.typical apparatus adapted to carry out the present improved method orprocess.

The steps of theprocess w1ll first be set forth and such detaildescription of the fapparatus then given as is deemed necessary.- f f YThe raw ore, whlch as mlned-contam's a vttf'wo hoursand one, hour.

verts theyalunnn-i (to a controllable extent) 'BENEFICILTION 0F DRES.

1925.. Serial No. 28,090.

overflow ,of minus mesh`being removed' and the remaining coarsedischargeV being wet ground to the same tineness as. the overflow. Thetwo products are then placed together and constitute, in effect, the rawmaterial ot the process. Atypical analysis of such material wherederived from the aforesaidCuban ores, ignoring the water content, is asfollows t Dry iron :v 45.00%, phosphorus: .020%,

silica: 4.50", alumina: liatl'n, Inanganese:` l

0.752%-, chromium 1.50%. nickeli 0.80%, loss on ignition: 125.30%. I

Such raw material is next dewatered in a suitable machine. preferably acontinuous Oliver ilter.anil thereupon such' dewatcred ore is intimatelymixed with soda ash (sodium v cai'bonatc), either dry 'or asv aslurry,iin the proportion of one ton of ore to fitr-t0 pounds, more orless, ot' soda ash.

.i v This mixture ot soda ashV and ore is then roasted, under oxidizingconditions, ata temperature varying between 7.-'30-o C.: `and l.,depending upon the time of' roast, wliich may varycorrespondinglybetween This roast conandthefchrop'iium into watersoluble sodi'- um salts.. f'

As "a resulty ot Isuch roasting, moreover,

substantially-all tree and combined water and 'volatiles will be drivenott 'from the mixture. After the latter has been cooled somewhat it isthen leached -withhot water,

as a result ot which the aforesaid sodium salt-s ot aluminumand'chromium will"be.,

dissolved out. This solution is conveyed into a precipitating tankwherev carbon diioxide gas, either from a suitable. generator or frompurified combustion gases, is passed therethrough, precipitating thealumina which lsettles out. The remaining solution is evaporated,duringwhich'evaperation the ychromium saltscrystalize out andthe excesssodium carbonate is recovered to be used over in the laforesaid roastingstep; or else a suitable precipitating agent is used to precipitate suchchromium, either as such or in the form Oia .saltpandthe re# main'ingsolution is vthen evaporated ddwn again, as just stated.

to proper soda ash strength tobe'nsedover The consumption of soda ashrequired in the foregoing stage of thev process will be approximatelyfifty pounds per ton otv leached ore. The aluminum will be removed fromtheoriginal ore to an extent varying from substantially all thereofr toany desired percentage. All but a trace of the chromium will be removedfrom suoli original ore and the leached ore Will now contain between 58per cent and -62 per cent of natural iron. depending upon the ext-ent ofremoval of alumina.

The next step in the, process is to intimately mix the, leaehed ore withfinely ,ground pyrite. in the ratio of one ton of such leaehed ore to450 pounds oi pyrite, more or less. depending on the condition of the.ore and the time allowed for the succeedinf.,r step. This step consistsin roastinnr the aforesaid mixture under oxidizingf conditions at atemperature varyinglr between 460 (l. and 700 C.. depending on the time,ot roast` which may vary correspondingly between one hour and twent)7minutes. As a result of' this step all or substantially all ot' the.contained nichel is converted to water soluble. nichel sulphate.

'l`he roasted mixture of ore, and pyrite is then cooled aml leacbed withhot water. The solution after the leach will carry the nickel as nichelsulphate and is conveyed to a tank, with or without evaporation to aconcen# trated form. where the nichel deposited on cathodeseleetrolytically. or else the solution is treated with a proper reagentthat will precipitate the nickel as such or in the form of a salt.

The ore now freed of constituents: loss on ignition, ,alumina` chromiumand nickel, androntainine' a high percentage of iron, but in a. finelydivided form and wet from the last leaching, is dried and agglomeratialin a. suitable sinterinfr machim` giving an iron ore fit 'for blastfurnace smeltil'igf. The filial product is a` merclmntable. Bessemeriron oie containingl between 5S percent aml (i2 per cent natural iron.ln addition, as a result ofl the several purificationand extractionsteps; 3M) pounds, more. or less, of pure alumina is obtained` about 40pounds of' chromium salts aml about IS pounds of nichel from between oneand eight-tenths and two tons 'ot' mined Cuban ore havingapproximatclythe analysis hereinbefore given. rlhe present process renders thebenehciatioraml purification of such ores economically and commerciallyfeasible and, as may be readily shown, will yield a substantial marginol' profit on the extraction and treatment of such ores.

The equipment illustrated in the drawing, it will be understood,constitutes but a single unit of a plant designed for carrylng out thepresent improved process. It

will also be understood that in referring to special items of suchequipment there is no intention to imply any limitation, but'that anyequivalent piece 'of apparatus suitable for carrying out the operationinvolved may be substituted.

The first element in such illustrative equipment, as previouslyindicated, consists ot' a Dorr bowl elassifierl. in which the overflowremoves the minus ,G0 mesh ore and the coarse discharge is wet-crushedto the same fineness as such overflow. 'lhc two proiluctrs are. thenintermixi-al and discharged onto a continuous dewatering device 2.preferably an Oliver continuous filter, which ".will dewater thecollected fine orc from the aforesaid wet classifier and wet grinder.One such Wet classifier, wet grinder and dewater-` ing machine willordinarily sufiicc to prepare enough crude or for a number, e. e. five,o'f the succeeding beneficiating units which will now be. described.

The first element in cach such unit is a suitable mixing device such asa pu;y mill` in which the fine and dowat'ered ore is intimately mixedwith the proper amount of soda ash. either in a dry state or as aslurry. The mixture -from such mill is t'l'un received in a continuousdryinu' and roasting' and cooling'and leachingy machine At, wherein thesoda ash roasting,r aml the. succeeding leachingr steps areaccomplished. This machine will preferably include a traveling panconveyor with screened bottom` onto which the. mixed ore and soda ash isfed in a bed ot between four and eifrht inches in depth and from 4fourto six feet in width. Such conveyor first carries the mixture under-adrier hood 6 that is heated by waste ga from the f`\.\llowin,g`roasting' hood 7, thes waste ,frases beingr drawn down through the orebed as it slowly travels alone; this zone liv-means ol an exhaust hood 8placed beneath the conveyor. v'lhe dried ore bed on the conveyor is nextcarried under such roast ing hood 7, where heat, varying between 750 C.and 900" (l. is supplied by means of coal or oil, or mixed coal and oilburners, or by elect ric heaters. the products of conibustion being'drawn down through the ore bed by means of' an exhaust hood t) placedbeneath the conveyor. As will be readily understood it is in thisroasting zone that the alumina and chromium are converted to sodiumsalts aml aty the same time. the volatile constituents that figure asloss on ignition" in the analysis of the raw ore. ari` driven out. Thelconveyor finally travels through a cooling zone where cold air is drawndown through the orc bed by means' of a third exhaust hood 10 placedbeneath theI conveyor as before.

The ore bed on such conveyor` which, as indicated, ends atabout the endot such cooling zone, .is then picked up by an endless traveling ltersheet 11, composed ot' a suit Lorente -ahle Filtering-material,supported on a belt of suitalolescreening, which passesunlerneatlraseries of jets 12 of hot Water. ouch Water, `clizirgecilwith a certain amount of steam or. not as, found preferable in theparticular operation, leaches out the sodium salts, the 'filtering ofthe leaching solution heingaided hy a suction'ho'od placed beneath thetiltdr sheet, which serves'to draw the solution down through the orehed.

At the end ofthe-leaching zone tlul ma:

- terial. is dischii-'iired Yfrom the filter sheet into' a suitablemixing device 14- which intimately mixes the le'ached orc with theproper amount ot iineiy ground pyritc and the nun ture is thencedischarged on to the succeeding machine 15, which 1s a substantialduplicate oi the machine 4 except that its length is'somevvhat less, orelse its speed greater inasmuch as the action with the pyrite is morerapid. As clearly indicated on the drawing the ore bed as received fromthe mixing device 14 is irst'convcyed through a dryingl zone and then insuccession through a roasting zone, a cooling zone and a leaching zone.inthe latter, jets of looilingiwater leach out the nickel sulphate inthe same manner as the water soluble aluminum and chromium salts Wereleached out in the preceding machine. At the end of the leaching zonethe solid residuum is discharged onto a sintering machine 16 of standarddesign, which is adapted to agglomerato the iinely divided material anddischarge the same in theform o'f a merchantahle iron orc suitable forblast furnace smelting. Ordinarily one such sintering machine will servea plurality, e. g., tive of the heneiiciatinp; appara tuses, just as acorresponding number of the latter will loe supplied for one classifier,

grinder and filter.

in both machines 4 and 15 stationary ralobles (not shown) are placed atproper intervals across the traveling ore hed through the entire lengthof the machine, i. e., in all of the component zones thereof, to agitatothe ore hed in order that the several aforesaid actions may he mostefficiently performed. It will he understood of course that thc lengthsoi' the several zones, as indicated in the drawing, are only approximateinasmuch as these will he determined hy the speed o't travel oi the orchcd, or vice versa.4

The solutions from the leachingr Zones in n'iachines 4 and l5 areconveyed to suitable tanks 17 and 18, rcspectivelyl and such solutionsthere trei'ited 'iii the .manner hereinn before forth in order torecover the alumina, chrome salts and soda ash in the one caso and thenickel in the other. rlihe leaching water l'rom the two machines willdesirahly hc heated in a suitahle heat ezichangc device 19 hy thc wastegases from the roasting zones ot said machines 7llhe exlviau-sting`hoods will he provided with proper bypasses and the desired degree ofvacuum obtained hy means of.v an c\hausting` fan or its equivalent.

The small manganese content present in the original ore, as indicated inthe analysis hercinhc'fore given, may remain in the linished product ornot without all'ectingr the beneficial results ol the trcatu'ient thatconstitutos the present invention. Any' roten `curo to the dispositionol such manganeso has accordingly been omitted.

Other modes oi' applying thc principle ol my invention may he employedinstead oi` 'the one explained, change being made as rcgarde the stepsherein disclosed, provided those stated by any of the following claimsor their equivalent he' employed.

l therefore particularly point out and distinctly claim as myinvention 1. In a method of beneiciating an oxidized iron ore ormetal-hearing product containing aluminum, the step which consists inroasting; such orc with soda ash under oxidizing; conditions, whereby acontrolled amount et such aluminum is converted into a water-solublesodium salt.

2. lin a method of heneiciating an oXi dized iron ore or metal-hearingproduct containing,r aluminum and chromium, the ste which consists inroasting such ore Witi soda ash under oxidizing; conditions and at a'temperature of approximatelydo' to 950 C., whereby the chromium and acontrolled amount of the aluminum are converted into Water-solublesodium salts.

3. In a method of beneiciating an oxidized iron ore or metahhearingproduct containing aluminum and chromium, the ste s which consist inroasting such ore with so a ash under oxidizingnr conditionsk and at atemperature of approximately 750 to950" C., whereby the chromium and acontrolled amount of the aluminum are converted into water-solublesodium salts, and then leaching out such salts.

4. in a method of henciiciatine' an oxidized iron rore or metal-hearingproduct containing aluminum, the step which consists in roastingsuch orewith soda ash, Wherchy a controlled amount ot such aluminum is convertedinto a Water-soluble sodium salt.

5. In a method of heneticiati'ng an oxi dized iron ore or metal-hearingproduct. containing aluminum and chromium, the ste which consists inroasting such ore with so ia'ash,"vvherehy the chromium and a oontrolledamount of the aluminum are vertcd into Watersoluhle sodium salts.-

6. lin almethod of heneiciating an oindiz-ed iron ore or metal-hearing,rproduct containingaluminum and chromium, the' steps which consist inroasting such ore with soda ash, whereby the chromium and a controliedamount of the aluminum are converted into coni Witter-soluble sodiumsalts, and then leachlto infr out such salts.

Y. l'n a method of beneliciating an oxidized iron ore ormetaLhearingproduct con taining aluminum. chromium and nickel, the steps whichconsist in 'roast-imgr such ore with soda ash, whereby the chromium anda controlled amount of the aluminum are couverted into water-solublesodium salts; leaching out such salts: roasting thc residue with asulphur-bearing; material, wherebyy the nickel is conrcrtcd tou'ater--soluhlc nickel sulphate; and then leaching out such .sulphate.'

8. ln a method ol bcneliciatinrf.r an oxidized iron ore or mctal-hcaringproduct containing' aluminum, chromium and nickel, the steps whichconsist in roasting such ore with soda ash, whereby the chromium and acontrolled amount.- ol` the aluminum are converted into Water-solublesodium salts; leaching out such salts; roasting the residue with arsulplniuhearing material, whereby the nickel is converted towater-soluble nickel sulphate; and then leaching'out such sulphate, suchfirst roastingY step bcing conducted at a higher temperature than thesecond.

l9. ln a method of bencliciating an oxidized iron orc or metal-hearingproduct. containing aluminum, chromium and nickel, the steps whichconsist in roastingr such orc with soda ash, whereby the chromium and aycontrolled amount of the alumium are converted into water-soluble sodiumsalts; leaching out such salts; roasting the residue with asulphur-bearing material, wherebythe nickel is converted toWater-soluble mckel sulphate; and'then leaching out such sulphate, hothof the foregoingr roasting: steps being conducted under oxidizingconditions.

10. In a method oli hcneticiating an oxidized iron ore or metal-hearincYproduct containing,r aluminum, chromium and nickel, the steps whichconsist in roasting,Y such ore with soda ash, whereby the chromium and acontrolled amount of the aluminumf are converted into water nluolesodium salts; leaching out such salts: roasting the residue with asulphur-hearing 'materiah whereby thc-nickel' is converted toWater-soluble nickel sulphate; and then leachingT out such sulphate,both ol the 'fore-r going roasting steps being' conducted underoxidizing conditions, and the first such step beingF conducted at ahigher ten'iperature than the second.

1l. 1n a method of heneticiating an oxidized ore or metal-bearingproduct containing almninum, chromium and nickel, the steps whichconsist in roasting such ore with soda ash, whereby the chromium andcontrolled amount oi the aluminum com verted into xi'ater-soliihiesodium salts;

Larnaca leaching out such salts; roasting the residue with asulphur-bearing material, wherehythe nickel is converted to waleusolublenickel sulphate; and then leaching out such sulphate,`V such lirstroastinlgr step beingr conducted at a temperature ol' approximately.750O C fto 950 C., and such second roasting step at a temperature ofapproximatcljy 460" C. to T00 C.

l2. ln a method of hcncliciating an oXidized iron ore or metal-bearing:product containing aluminum', chromium and nickel. thc steps whichconsist in roasting such orc with soda ash, whereby the chromium and acontrolled amount ol" the aluminum are converted luto water-solublesodium salts; leachinglr out such salts; roasting the residue with asulphur-bcaring,r material, whereby the nickel is converted lowater-soluble nickel sulphate; and then leachingont such sulphate. hothof the foregoingv roasting steps beingr conducted under oxidizingconditions, and such first roasting stop being,r conducted at atemperature of approximatelb'l'fillo to 950 (l. and such secondroastincr slcp at a tcmpcraturc of approximately f-ltillo (l. to T00"(l. v

ll. ln a method of bcncliciating;r au oxidized iron orc or metal-bearingproduct con taining,r aluminum, chromium and nickel, the steps whichconsist in converting thc aluminum and 'chromium into the form ofwatersoluble salts; leaching ont: such salts; and then convertingr thenickel into the form of P. watensoluble salt and leachinglr out suchsalt.

14. ln a method of b'eneiciatimgT an oxi- Adizcd iron ore ormetal-bearing,r product containing aluminum. chromium and nickel, thesteps` which consist in'convertingr the aluminum and'chromium into theform vof Watersoluhle sodium salts; leachingout such salts: and thenconverting the nickel into the form ofl a water-soluble salt andleaching` out vsuch. sa t.

l5. ln a method of benetic'iating an oxidized iron ore or metal-hearingproduct containing aluminum, chromium und nickel, the steps whichconsist in converting the aluminum and chromium into the form ofwatersoluole salts; leachingr out such sa ts; and

then converting the nickel into nickel sul'- phate and leaching out suchsulphate.

16. In a method of beneficiatingr an oxidized iron ore or metal-hearingproduct containing aluminum, chromium and nickel, the steps whichconsist in converting the aluminum and chromium into the form ofwatersoluhle sodium salts; leaching out such. salts; and thenconverting' the nickel into nickel sulphate and leaching out suchsulphate.

17. ln a method ot heneticiating an oxi-l dined iron orc ormetahbearing;product containing: aluminum, chromium and nickel, the stops whichconsist in converting the' alumiend .chromium into the form of waterwww2 soluble salts; leaching out such salts; then converting the nickelinto *aim fami of a water-soluble V'sziit and leaching ou@t smh snit;and aggiomerating the solici fesidnum 18. In :i method of beneciating mioxidzed iron ore or metzilbearing pi'uc c011- tainng aluminum, chrmiuinami minitel, the seps which consist in converting h@ alumi num into theform of Water-soiuble salts; leaching out `such salts; than convertingtbn 10 nickel int-0 the form of a water-soluble salt und leaching outsuch salt; and sntering the Snid residuum.

Signed by me, this Qn day ofMay, 1925.

@MDE P. MCCORMACK

